Apparatus for production of uniform specimen coatings



March 5, 1957 K. R. FISCH EIAL APPARATUS FOR PRODUCTION OF UNIFORM SPECIMEN COATINGS Filed Nov. 50, 1955 INVENTOR.

KURT R. FISCH BY 1 HENRY GISSER M W Wm M. Q M C W m F 2,783,734 IC pat nted Ma 5, 957

APPARATUS FOR PRODUCTION OF UNIFORM SPECIMEN COATINGS Kurt R. Fisch and Henry Gisser, Philadelphia, Pa., as-

signors to the United States of America as represented by the Secretary of the Army Application November 30, 1955, Serial No. 550,226

1 Claim. (Cl. 118-404) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

Our invention relates to evaluation of the protective properties of semi-fluid substances. More particularly, the invention is directed to apparatus for attainment of uniform coating of specimen surfaces with grease-like substances whose performances in the role of corrosion prevention are desired to be measured.

Reliability of results in the envisaged measurements is dependent basically upon the ability to repeatedly pro duce a uniform coating or test film of the substance under investigation. That is to say: that the thickness of the applied film should closely approach uniformity over an entire test surface; that the film thickness of a given substance applied to several standard test-surface specimens should be substantially the same; and the thickness of film of various related substances under comparison, applied to corresponding sets of standard test-surface specimens, should be substantially the same.

The work which led to the apparatus of the present invention dealt in particular with appraisal of the rust preventive value of greases.

Various devices for producing specimen films of controlled thickness have evolved in the protective and decorative coating industry, in response to a need of spreading for evaluation paint and varnish in uniform thicknesses over flat test surfaces. Those devices include single and double-action spinners, manual and automatic doctor blades, dip coaters and others, as described in Physical and Chemical Examination, Paints, Varnishes, Lacquers, Colors by Gardner and Sward, th edition, Chapter 9.

Devices of the cited kind were found unsatisfactory for determination of the rust-preventive properties of greaselike substances. The reasons were seen to be: unproducibility, within practical limits, of fiat surfaces in themselves of sufiicient uniformity to base a coating of a degree of evenness essential to valid results and pronounced edge effect at the extensive perimeter of flat testsurface specimens, which effect is a creeping of moisture under the coating at the edges whereby results are vitiated.

It was visualized that cylindrical test-surface specimens at once would facilitate attainment of required uniformity of surface and minimize edge effect. Consequently we set as our object a provision of apparatus adaptive of cylindrical specimens and requiring but ordinary manipulative skill in use.

We now have accomplished that object by providing a combination of: means for manipulatively holding a cylindrical, test-surface specimen; means cooperating with the holding means to reciprocatively guide the latter; and means associated with the guiding means for housing and confining a grease-like substance under pressure cooperatively with the specimen; so that upon completion of a reciprocatory cycle of the holding means, a film of desired character of the grease-likesubstance is caused to be desposited upon the specimen.

The specific structures of an embodiment whose eifectiveness in use has been established are illustrated in the accompanying drawings wherein:

Figure 1 depicts, sectionally in part, the several elements of the structures in their relationship when housing a test substance preparatory to use.

Figure 2 reflects similarly the relationship of components when confiing a grease-like substance under pressure and the holding structure has been manipulated to the limit of its stroke inwardly of its guiding structure.

Figure 3 shows the relationship when the holding structure has been retracted, and partially disengaged of its guide.

Figure 4 represents the holding structure separate from the other structures of the embodiment.

Reverting to Figure 1, the numeral 1 designates a cylindrical test-surface specimen. 2 is a piston-like holder of the specimen, having a central bore 3 in which one end of the specimen is concentrically seated. 4 is a bore vent to facilitate seating of the specimen. 5 is a setscrew for locking the specimen in the bore. 6 is a handle unitary with the holder. The foregoing structure exemplifies a means for manipulatively holding a cylindrical test-surface specimen.

7 is a tubular guide for the holder 2. The lower end of the guide is open so as to allow withdrawal of the holder and specimen assembly. A vent hole 12 is provided to conserve ambient pressure within the guide during reciprocation of the holder. This tubular guide is exemplary of means cooperative with the holder to guide the latter as it is caused to be reciprocated.

The upper end of the guide is flanged, and is fashioned to form interiorly of that end a chamber 8, having a rigid, non-deformable wall, which chamber serves as a reservoir for the grease-like substance to be deposited on specimen 1. As shown in Figs. 1 through 3, this chamber is in the form of a truncated cone so as to provide internally a central aperture 9 which is coaxial with holder 2; the diameter of that aperture being larger than the diameter of specimen 1, depending upon the thickness of the coating to be applied, but being smaller than the diameter of holder 2. A flanged, internally threaded adapter 10 is mated with the flange of the guide '7 and secured thereto coaxially with respect to chamber 8. An externally threaded cap member or gland 11, centrally apertured for slidably supporting the specimen and cooperative with the adapter, provides, in conjunction with the specimen when the latter is engaged within the member 11 (as shown in Fig. 2), for confinement of the grease-like substance within the chamber under pressure. The foregoing structure exemplifies means associated with the guiding means for housing and confining a greaselike substance under pressure cooperatively with the test-surface specimen.

The mode of use of our apparatus is as follows:

A cylindrical test-surface specimen 1 is inserted, seated and locked in holder 2 with set-screw 5 (see Figure 4). The holder is then inserted into guide 7 (see Figure 1) and advanced in the guide until the upper extremity of the specimen just enters aperture 9 of chamber 8. The chamber then is filled with the grease-like substance with which it is desired to coat the specimen. Thereupon cap member 11 is threaded partially into the adapter 10 and holder 2 advanced in its guide fully to the position illustrated in Figure 2, in which position the aperture in cap member 11 is completely filled by the specimen. Now the cap 11 is tightened, with small torque so as to exert a pressure on the grease-like substance. Then holder 2 is withdrawn from the guide 7 with an even motion to produce upon the specimen a uniform coating. The specimen may be perforated as at 13 to receive a wire or the like for facilitating further handling of the specimen without injury to the coating.

We have evaluated the performance of our apparatus according to the following method:

Cylindrical test-surface specimens whose diameters For evaluation of effect of certain inherent variables, the data were subjected to ananalysis of variance, according to Statistical Manual, Methods of Making Experimental inferences by C. W. Churchman, June 1951. The analysis was directed to:

had been measured at various points to the nearest .0001 a Adeauac of a aratus (tolemn t (1 inch (2.5 microns) for control of specimen uniformity cohcenizricit pp algnmen an were coated in the apparatus with various greases. The Variation in ciaracter amen eas specimens then were cleaned of coating in an arc of sur- Dimensional irre ularities es face along their entire length and measured in diameter 10 g 1 p clmens with a traveling microscope from points upon the uncoated surface across the undisturbed thickness of coat- The data of determinations 1-4 and 5-7 were anaing, so as to avoid error through compensating ununilyzed separately. The hypothesis used, H0, was that the forrnmes of coating at opposlte points. main variables and their interaction had no significant The measurements were made with six different greases l5 influence on results. The probability of a Type I error on sets of four spec1mens per grease. The main comtl1e error of rejecting Ho when H is actually trueponents of the several greases were varied as follows: was set at .05. From the analysis- A-Lithium soap and diester. BLitbium soap and mineral oil. C--Diatomaceous earth and diester. 20 Determinations! 04 DLithiurn soap and mineral oil diester blend. E--Silica gel and diester. F-4odiurn soap and mineral oil. u f Degrees ean Contribu- Squares 01 Square F Significance Four points were measured on each specimen at an Ofdev Freedom, (0.05 interval of approximately inch. The same specimens 25 "p ere cleaned, recoated and agam measured, this time at 814 [L859 Notsigmficanh three pomts along each specimen, to evaluate repro- 5 1028.09 108. 51 Significant.

3 7. 39 0.780 Notsignificant. ducibility. The 1 sults are given in the table below, in 15 10,80. L140 Notsigmficant. which the values for the four points of original measure- 9 17. 42 1. 838 Not significant. ment upon each specimen appear as Determinations Nos. 15 5515 5'821 slgmfican 45 9.4747 1.000 1, 2, 3 and 4, and the valuesobtained at three points on each specimen after recoating appear as Determina- 95 tions Nos. 5, 6 and 7.

ORDNANCE CORPS Patent Specification sheet Grease Coat Thickness (Microns) Grease A B G D E F Specimen No. 1 2 a 4 5 0 7 s 0 10 11 12 13 14 15 1e 17 18 19 20 21 22 23 24 Determination No.2

1 49 01 55 55 54 01 5s 42 39 44 41 51 53 46 47 63 59 55 64 01 55 01 2 47 e0 50 70 01 01 0s 45 4s 44 47 57 45 4s 54 54 55 02 52 53 54 5s 53 04 04 70 01 47 39 43 43 40 57 49 50 01 50 61 5s 54 59 55 5a 4855 4a 57 70 09 e3 37 41 4233411574848 59 00 55 63 00 50 5s 58 53 15 5s 53 59 64 55 41 41 37 10 53 51 51 4s 62 00 62 57 63 5a 50 00 51 4s 55 57 5s 61 00 47 43 44 40 50 50 4s 50 53 01 00 51 51 51 55 02 4s 52 52 55 03 50 05 51 as 41 43 4s 53 4s 51 54 55 57 00 55 5 55 51 Mean per columi is 44 49 53 53 60 64 64 62 44 39 43 41 49 54 48 48 59 58 58 61 61 55 57 58 Mean per grease X 50 62 42 50 59 58 Grand meani 54 Overall Standard deviation 'l s The frequency distribution of the grease thickness (L D 't i t'i 't y measures appears below:

X 21.00 2 10.50 0.7 11 Notslgnifieant. Grease 5 530.90 41.54 Significant. flgizz cclgtzgs 1(15.05 42g iiotsignitgcant. i z 1 .08 .78.. Notsigni cant. A B C D E F 0 0.95 0.493 Notsigmficant. 15 23:22 1. 639 'Notsignificant. 30 14.1007 1.000

2-2 Total. $014.03 71 12:5

g i Measurements along specimens. 0 2 Measurements on difierent greases. Measurements ondlfierent, specimens.

4 2 Total 28 28 28 28 28 28 168 mm The followingconclusions maybe drawn: the apparatus 1 9 produces a uniform coating and is capable of reproducing Range (microns) 22 15 10 12 11 3 v5 the coating upon several test-surface specimens and with various greases. The thickness of film may vary within Total range 35-70 microns 75 Average range 15 microns a limited range (35-70 microns)- among greases differing in texture and consistency, but uniformity of film is unaffected.

From the foregoing it is evident that we have provided apparatus, adaptive of cylindrical specimens and requiring but ordinary manipulative skill in use, that is capable of producing a uniform coating reproducibly and which consists of a combination of: means for manipulatively holding a cylindrical test-surface specimen; means cooperating with the holding means to guide the latter as it is caused to be reciprocated; and means associated with the guiding means for housing and confining a grease-like substance under pressure cooperatively with the specimen; so that upon completion of a reciprocatory cycle of the holding means, a film of desired character of the grease-like substance is caused to be deposited upon the specimen.

In practicing our invention, the holder and guide must be closely fitted. The bore in the holder, the chamber aperture and the aperture in the cap must be aligned and concentric. In the prototype that yielded the results herein reflected, we utilized specimens varying in diameter from 9.100 mm. to 9.134 mm., and a chamber aperture whose diameter measured 923311002 mm.

The structure shown and described herein is exemplary and accordingly should be considered illustrative, not limitative.

We claim:

Apparatus for applying to substantially straight, cylindrical specimens a uniformly dimensioned coating of a grease-like substance, such apparatus comprising: a guide having an opening therethrough which opening comprises a conical, first portion and a coaxial, cylindrical second portion having rigid, non-deformable walls, the conical portion serving as a reservoir for the grease-like sub stance, the conical portions smaller diametered end being adjacent to the cylindrical portion but being smaller than the diameter of that portion, and the conical portions smaller diametered end being larger than the diameter of the specimen depending upon the thickness of the coating to be applied; a holder adapted to receive the specimens one at a time, said holder fitting into and being slidable in the cylindrical portion of said guides opening so that a specimen in said holder is passable coaxially through said guides conical portion; an internally threaded adapter ring attached to said guide adjacent to and in alignment with that guides reservoir; and an externally threaded gland in said adapter, said gland being usable to exert pressure on the grease-like substance, the inside of said gland being coaxial with respect to the specimen and being of such size as to slidably accommodate the specimen.

References Cited in the file of this patent UNITED STATES PATENTS 1,949,234 Baxter Feb. 27, 1934 2,141,852 Bingham et a1 Dec. 27, 1938 2,331,983 Kaiser Oct. 19, 1943 2,359,751 Cummings et al. Oct. 10, 1944 2,649,757 Diamond Aug. 25, 1953 

